酪氨酸衍生物的不溶性聚合物存在于皮肤中并导致皮肤变黑（皮肤色素沉着） insoluble polymers of tyrosine derivatives found in and causing darkness in skin (skin pigmentation), 头发 hair, 和羽毛可防止日光灼伤。胡萝卜素产生黄和红。皮肤黑素是由黑素细胞产生的 and feathers providing protection against sunburn induced by sunlight. carotenes contribute yellow and red coloration. Dermal melanin is produced by melanocytes, 在表皮的基底层中发现。尽管 类皮肤中黑素细胞的浓度通常相似 which are found in the stratum basale of the epidermis. Although human beings generally possess a similar concentration of melanocytes in their skin, 某些个体和种族中的黑素细胞更频繁或更不频繁地表达产生黑素的基因 the melanocytes in some individuals and races more frequently or less frequently express the melanin-producing genes, 从而赋予或多或少的皮肤黑素浓度。一些个别的动物和 类的体内没有或只有很少的黑素 thereby conferring a greater or lesser concentration of skin melanin. Some individual animals and humans have no or very little melanin in their bodies, 这就是苦参。 which is a condition known as albinism. 较高的Eumelanin水平也可能是不利的 Higher eumelanin levels also can be a disadvantage, 然而 however, 除了对维生素D缺乏症的高度重视之外。深色皮肤是激光去除口酒污渍的复合物因素。有效治疗白皙的皮肤 beyond a higher disposition toward vitamin D deficiency. Dark skin is a complicating factor in the laser removal of port-wine stains. Effective in treating fair skin, 通常，在亚洲 和非洲 后裔中，激光在去除葡萄酒酒渍方面效果不佳。肤色较黑的 中较高的黑素浓度仅会扩散并吸收激光 lasers generally are less successful in removing port-wine stains in Asians and people of African descent. Higher concentrations of melanin in darker-skinned individuals simply diffuse and absorb the laser radiation, 抑制目标组织的光吸收。黑素同样会使皮肤较黑的 的其他皮肤科疾病的激光治疗复合物化。 inhibiting light absorption by the targeted tissue. Melanin similarly can complicate laser treatment of other dermatological conditions in people with darker skin. 在显微镜下黑素是棕色的 Under the microscope melanin is brown, 苯乙醛是一种重要的与氧化有关的醛。暴露于苯乙烯会产生苯乙醛作为次生代谢产物。苯乙烯被认为是 毒物 non-refractile and finely granular with individual granules having a diameter of less than 800 nanometers. This differentiates melanin from common blood breakdown pigments which are larger, 块状且易折射，颜色范围从绿到黄或红棕色。在色素沉着的病变中 chunky and refractile and range in color from green to yellow or red-brown. In heavily pigmented lesions, 黑素的密集聚集体会掩盖组织学细节。高锰酸钾的稀溶液是一种有效的黑素漂白剂。 dense aggregates of melanin can obscure histologic detail. A dilute solution of potassium permanganate is an effective melanin bleach. 导致皮肤变黑的色素 Pigments causing darkness in skin, 头发 hair, 羽毛 feathers, 等是不规则的聚合物结构，分为三类 etc. They are irregular polymeric structures and are divided into three groups: 植物界中的异源黑素 allomelanins和动物界中的洋红素 葡聚糖 eumelanins和蝴蝶素 phaeomelanins。 当皮肤色素沉着作为种族特征与社会地位或其他 类属性相关联时 When skin pigmentation as a characteristic of race is linked to social status or other human attributes, 这种现象被称为种族主义。许多 和社会将种族主义与种族主义观念和制度重叠，这些观念和制度任意赋予 们以一种固有的优越感或自卑感 this phenomenon is known as racialism. Many people and societies overlay racialism with racist perceptions and systems which arbitrarily assign to groups of people a status of inherent superiority or inferiority, 基于肤色或种族分类的特权或劣势。种族隔离时代的南非是白 至上主义社会的一个例子，它基于肤色对权力和特权进行分层的系统 privilege or disadvantage based on skin color or racial classification. Apartheid-era South Africa is an example of a white supremacist society based on a system of stratification of power and privilege by skin color, as 好 well as 种族的 racial 混合物 ad混合物 mixture. 类似 Similar 例子 例 examples can be 发现 found in Brazil's 高度 highly 社交上 社会的 socially 颜色分层 颜色 color-stratified 社会 society; and, 在美国。 in the U.S., 白 控制和黑 控制机构的种族隔离和制度种族主义 segregation and institutional racism on the part of white-controlled and black-controlled institutions, and 内部 internal '颜色 color 意识 consciousness' on the 部分 part of some 民族 ethnic 少数族裔 minorities. 偏见 Prejudice 反对 against people with 更多 more 高度 highly 着色的 颜料 pigmented skin is the 最 most 无处不在 pervasive form of 颜色 color 偏压 bias. 许多 Many other 社团 societies 保持 remain 非正式地 informally 分为 divided on the 基础 basis of skin 颜色 color and, 经常 often, 相关种族。 （另请参阅殖民主义 related ethnicity. (See also colonialism, 纳粹主义 Nazism, 色素专制和制度种族主义。） pigmentocracy and institutional racism.) 因为黑素是小分子的聚集体 Because melanin is an aggregate of smaller component molecules, 蜡状的。非常实质性的ct告诉我们它有一种“强大而甜美的菠萝味”。比己酸烯丙酯更顺滑，更甜。果味类似于乙酸芳樟酯。从四月到七月收获的。切割后立即将新鲜原料加工，以充分保留芳香性。莳萝精油具有新鲜的特征 there are a number of different types of melanin with differing proportions and bonding patterns of these component molecules. Both pheomelanin and eumelanin are found in human skin and hair, 但是Eumelanin是 类中最丰富的黑素 but eumelanin is the most abundant melanin in humans, 以及最有可能缺乏苦参的形式。 as well as the form most likely to be deficient in albinism. 在皮肤中局部存在黑素的地方会形成雀斑和痣。它们与皮肤苍白高度相关。 Freckles and moles are formed where there is a localized concentration of melanin in the skin. They are highly associated with pale skin. 黑素是一种生物聚合物和一种橙花肽。在1970年代初期 Melanin is a biopolymer and a neuropeptide. In the early 1970s, 约翰·麦金尼斯 John McGinness, 彼得·科里 Peter Corry, 彼得·普斯图尔（peter proctor）报告说，黑素是一种高电导率的有机半导体（科学 and Peter Proctor reported that melanin is a high-conductivity organic semiconductor (Science, 第183章 vol 183, 853-855（1974））。研究表明，黑素可作为电压控制的固态阈值开关。进一步 853-855 (1974)). Studies revealed that melanin acted as a voltage-controlled solid-state threshold switch. Further, 开关时它会发出电致发光的闪光。 it emitting a flash of light electroluminescence when it switched. 大约有十种不同类型的眼皮肤苦参 There are approximately ten different types of oculocutaneous albinism, 这主要是常染色体隐性遗传疾病。某些种族的不同形式的发生率较高。例如 which is mostly an autosomal recessive disorder. Certain ethnicities have higher incidences of different forms. For example, 最常见的类型 the most common type, 称为2型眼皮肤苦参（oca2） called oculocutaneous albinism type 2 (OCA2), 亚致死浓度的牛至属金黄熊果缺乏对金黄熊果的直接保护或交叉保护的诱导。肉类培养基中的精油和香芹酚。 is especially frequent among people of indigenous African descent. It is an autosomal recessive disorder characterized by a congenital reduction or absence of melanin pigment in the skin, 头发和眼睛。非洲裔美国 中oca2的估计频率为十分之一 hair and eyes. The estimated frequency of OCA2 among African-Americans is 1 in 10,000, 与36分之一的频率形成对比 which contrasts with a frequency of 1 in 36,白 中有000 。在一些非洲国家 000 in white Americans . In some African nations, 疾病的发生频率更高 the frequency of the disorder is even higher, 2分之1 ranging from 1 in 2,000比5 000 to 1 in 5,000.苦参的另一种形式 000. Another form of Albinism, the '黄 yellow 眼皮的 oculocutaneous 苦参 albinism', 在阿米什 中似乎更为普遍 appears to be more prevalent among the Amish, 他们主要来自瑞士和德国。患有这种ib变异的 出生时通常有白发和皮肤 who are of primarily Swiss and German ancestry. People with this IB variant of the disorder commonly have white hair and skin at birth, 但婴儿期会迅速发展正常的皮肤色素沉着。 but rapidly develop normal skin pigmentation in infancy. 宽广地 Broadly, 黑素是任何聚乙炔 melanin is any of the polyacetylene, 聚苯胺 polyaniline, and 聚polypyrrole '黑 黑 blacks' and "棕色 browns 棕色 browns" or their 混合的 mixed 共聚物 co聚合物 聚合物 polymers. The 最 most 共同 common form of 生物 biological melanin is a 聚合物 polymer of either either or 都 both of 二 two 单体 monomer 分子 molecules: 吲哚醌 indolequinone, 和二羟基吲哚羧酸。相反 and dihydroxyindole carboxylic acid. In contrast, 有点花香让 联想到番红花花；典型的藏红花 some fungal melanin is polyacetylene black. Melanin exists in the plant, 动物界和原生界 animal and protista kingdoms, 用作颜料的地方黑素在古细菌界和细菌界的存在是该领域研究 员不断争论的问题。 [hmdb] where it serves as a pigment. The presence of melanin in the archaea and bacteria kingdoms is an issue of ongoing debate amongst researchers in the field. [HMDB]